27. Concern has been expressed that the nuclear transfer procedure causes an unacceptably high loss of embryos, fetuses and of mature animals which are killed as part of the procedure. During the series of experiments prior to the birth of Dolly, two of the lambs that died had developmental abnormalities. In the experiment which produced Dolly, only one successful live birth resulted from 277 attempts using cells in which mature DNA had apparently been transferred. It is too early to say if nuclear transfer will result in a higher incidence of abnormality but this is clearly an area for further investigation. This presents both ethical and economic concerns to the farmer who may be perceived as trying to derive benefit from a procedure which involves unacceptable levels of loss. Indeed this view was presented as a concern to us by farmers themselves.
28. Recent reports from the USA concerning the birth of a calf produced by nuclear transfer from cultured fetal cells, implies that some of the technical challenges are already being resolved. The current level of loss is likely to decrease as technical knowledge and competence advance. Cloning techniques could eventually reduce the number of animals used in research which presently relies on more random genetic modification techniques. However, FAWC believes that the current levels of loss make it unacceptable to employ nuclear transfer as a routine procedure in agricultural practice.
29. Research is needed into the causes of embryonic and fetal deaths and of perinatal losses and birth abnormalities associated with nuclear transfer, and the scale of these problems.
30. On the other hand, we recognise that, prior to nuclear transfer, genetic manipulation in agricultural species was only possible through pronuclear injection where genes are added to the animal's own genes in a random fashion. The technology of nuclear transfer creates the opportunity for genes to be inserted in a targeted fashion and for recipient genes to be deleted, thus providing the opportunity for replacement of specific genes. It is also possible to test whether or not a desired gene has been incorporated into the nucleus before nuclear transfer takes place. Hence only the nuclei of the selected group of cells which carry and express the transgene would need to be transferred. This has the potential to reduce significantly the number of animals produced in experiments involving transgenesis in the agricultural species.